This paper presents a method for the dimensioning of the low-energy District Heating (DH) piping networks operating with a control philosophy of supplying heat in low-temperature such as 55 °C in supply and 25°C in return regularly while the supply temperature levels are being boosted in cold winter periods. The performance of the existing radiators that were formerly sized with over-dimensions was analyzed, its results being used as input data for the performance evaluation of the piping network of the low-energy DH system operating with the control philosophy in question. The optimization method was performed under different mass flow limitations that were formed with various temperature configurations. The results showed that reduction in the mass flow rate requirement of a district is possible by increasing the supply temperature in cold periods with significant reduction in heat loss from the DH network. Sensitivity analysis was carried out in order to evaluate the area of applicability of the proposed method. Hence varied values of the original capacity and the current capacity of the existing radiators were evaluated with the design temperature values that were defined by two former radiator sizing standards.
Energy and Buildings, 2015, Vol 88, p. 324-334
Boost temperature; Control philosophy; Low temperature; Low-energy district heating; Optimization; Pipe dimensioning; Sensitivity analysis